The left guide pole on the trailer looks like it's been doctored up - what's up with that?
Trailer looks a bit rusty on the back too. I'd poke around with a screwdriver and make sure it's not starting to crumble.

Ask about the engine and get the story behind that. Truck engine is not a boat engine...
How many hours on hull vs. engine if it was replaced?

I like the black PC tower - nice touch.
Looks like a good ballast setup.
Good cover, bimini, etc.

Other than that, just the usual deal with show me the records and receipts on it.

Personally I'd ditch the stainless prop ASAP and go with something that has the right pulling power.

Think he botched the engine description but that's a clean 22' boat, be realistic for 19k obo you are going to compromise, but it is a solid, reliable v-drive wakeboat. As long as its a stock engine lol!